Greasy finger traces can potentially reveal the pattern used to unlock Android devices. Typing a PIN is better, a Googler concludes.
A few swipes with a greasy finger using Android's pattern-unlock feature left clear traces on this Nexus S phone.

http://asset1.cbsistatic.com/cnwk.1d/i/tim/2012/02/14/20120214_Smudged_Nexus_S_001.jpg
A few swipes with a greasy finger using Android's pattern-unlock feature left clear traces on this Nexus S phone.
(Credit: Stephen Shankland/CNET)

Eat a lot of potato chips? Then consider avoiding one of the ways Google offers to unlock an Android device.

Google's mobile operating system lets people unlock devices by swiping a particular pattern across a three-by-three grid of dots. But Android evangelist Tim Bray raised a concern about "reverse smudge engineering" to figure out the unlock pattern.